Topping up turf infill: how to check depth and how much to add

01How can I tell my turf is low on infill?

• Blades that stay down. Press a patch lightly. Motz, an infill maker, says blades should bounce straight back, and spots that stay flat or matted may need more infill (Motz). If brushing alone stands them up, it was matting; see our guide to matted turf.
• Backing you can see. Part the blades with your fingers. FieldTurf Landscape, a turf maker, says infill should clearly cover the backing (FieldTurf Landscape).
• Too much blade showing. Shaw’s guidelines finish with ½ to ¾ inch of blade above the infill and warn that more exposed fiber mats or crushes under heavy traffic and wears early (Shaw).
• Turf that moves. Synthetic Grass Warehouse, a distributor, says turf short of infill can wrinkle, rupture seams or split its backing (SGW). See our guide to lifting edges.
• Sand somewhere else. The STC’s maintenance guidelines note that infill collects at the edges (STC maintenance guidelines). A drift along a border or the low side moved there.

On new turf, the STC says infill settles over the first several months of use and rain, and Motz says installers often put in too little: check depth once it has settled.

02How do I measure infill depth?

Motz measures from the base of the turf to the top of the infill, against the depth your turf’s specifications call for (Motz). No spec sheet? Ask the installer for the figure.

1. Use a gauge. The STC prefers an infill depth gauge, or a nail and a tape measure, read on a grid across the whole area, because an even depth matters as much as the average.
2. Add the spots that lose most. The path from the back door, the dog’s routes, below downspouts and the downhill edge.
3. Compare with the chart. Motz’s Envirofill guidelines accept a variance of about ¼ inch from its chart depths (Envirofill guidelines).

03How often does turf need a top-up?

There’s no single calendar, and the makers don’t agree on one:

Motz ties the interval to the infill type, how hard the area is used, the climate and weather, and the upkeep. A quiet front lawn may go well past a year; a dog run can need topping several times a year.

04What moves infill in a Northern Colorado yard?

• Storms. In heavy rain a small part of any infill floats and shifts, says Amorim, a cork infill maker (Amorim). Plains thunderstorms sometimes drop more than 4 inches in a few hours (Colorado Climate Center), and NOAA logged 536 hail reports in Weld County from 2011 through 2025, on 156 separate days (NOAA Storm Events). The STC advises checking infill after heavy rain in case it has migrated downslope. For hail damage, see our hail guide.
• Snow clearing. The Fort Collins station, nearest to Fort Collins and Wellington, averages 51.4 inches of snow a year (NOAA normals, 1991–2020). Amorim estimates 1 to 4 percent of a sports field’s infill can go in snow clearing in colder countries, and the STC warns that brushing off the last snow may remove infill too.
• Chinook thaws and foothill wind. The Climate Center describes chinook winds raising temperatures 25 to 35°F in a short time, and periodic, severe turbulent winds very near the mountains. Our reading, not theirs: a fast melt runs across turf like a heavy rain, so check the low edge after one, and check light organic infills, which Motz says migrate easily, more often.
• Blowers and hoses. Motz says a leaf blower held about 12 to 18 inches above the turf shouldn’t move infill (Motz); the STC adds minimal throttle, nozzle never pointed straight in. FieldTurf Landscape keeps a pressure washer below 1500 PSI, sprayed at an angle.
• Feet and paws. Motz says running children and pets move infill, and regions with four seasons and lots of precipitation see more movement. Here it’s more season than rain: the Fort Collins station averages 15.88 inches of precipitation a year.

05How much infill does turf need per square foot?

Makers’ figures for a full load, by pile height and infill:

Your turf’s spec sheet overrides these, as Motz itself says.

A top-up is a slice of those totals. A worked example on Motz’s chart (our arithmetic, not the maker’s):

• A lawn with a 1¾ inch pile should hold ½ to ¾ inch of infill at 2.5 to 3.5 pounds per square foot, so that quarter inch is worth about a pound per square foot.
• The gauge reads ½ inch along a 150-square-foot path from the patio door, and you want the middle of the range back.
• That’s about 0.5 pound per square foot, roughly 75 pounds: two 50-pound bags, the size Motz sells its coated sand in (Motz FAQ).

Spread it in thin layers and gauge between them; the second bag may not be needed.

06What infill should go back in, and does Firestone limit it?

As a rule, the same infill that’s already there. FieldTurf Landscape says to buy the type originally installed, and the STC says replacement infill should meet the builder’s specification. Coated sand is meant to be the whole fill: Motz says its coated sand works best alone and recommends replacing a different old infill rather than topping it, and a civil engineer writing for facility managers says coated-sand products are meant to be 100 percent of the infill, without silica sand mixed in (Gale Associates).

In Firestone the code sets the material and the upkeep. Infill “shall be a non-toxic anti-microbial material such as silica sand or acrylic coated sand,” and “Crumb rubber filler shall be prohibited.” Turf is to be maintained “to mimic healthy living turf,” kept free of depressions and excessive wear, with worn areas repaired to a “consistent appearance with the existing artificial turf” (Firestone Development Code 16.6.4). Topping up with the same silica or acrylic-coated sand stays inside that wording. Whether a walnut-shell or zeolite top-up counts under “such as” isn’t spelled out. It depends on how the town reads the wording; ask Firestone Planning. Not legal advice. More on the town in our turf rules guide and on the Firestone page.

07How do I add infill without overdoing it?

1. Pick a dry day. Motz says turf should be completely dry when infill goes down, so it doesn’t clump on the fibers (Motz).
2. Spot-fill by hand. For a few low spots Motz uses handfuls, a thin layer at a time, brushed in. For a bigger area FieldTurf Landscape uses a drop spreader and a broom. Brushing technique is in our matted turf guide.
3. Gauge again and stop in range. Motz says excess infill can impede drainage and leave the surface uncomfortably hard.
4. Get help for a yard-wide refill. Motz suggests an expert when infill is extremely low throughout.

Before buying bags, ask whoever installed the turf:

• What went in, and at what rate? You want a product name and a pounds-per-square-foot figure that fits the maker’s chart for your pile height.
• What should my gauge read? A depth or a blade reveal from the turf’s spec sheet.
• Does the turf maker’s coverage depend on infill level? It can: PreGra’s terms exclude failures from “removal or reduction of the infill system level” (PreGra). A straight answer shows you the clause.